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Abstract:
The highest antiferromagnetic (AFM) temperature in Ce based compounds
has been reported for CeScGe with T-N = 47 K, but its local or itinerant
nature has not been deeply investigated yet. In order to shed more light
into this unusually high ordering temperature we have investigated
structural, magnetic, transport, and thermal properties of CeTi1-xScxGe
alloys within the range of stability of the CeScSi-type structure: 0.25
<= x <= 1. Along this concentration range, this strongly anisotropic
system presents a complex magnetic phase diagram with a continuous
modification of its magnetic behavior, from ferromagnetism for 0.25 <= x
<= 0.50 (with 7 K <= T-C <= 16 K) to AFM for 0.60 <= x <= 1 (with 19 K
<= T-N <= 47 K). The onset of the AFM phase is associated to a
metamagnetic transition with a critical field increasing from H-cr = 0
at x approximate to 0.55 to approximate to 6 T at x = 1, coincident with
an increasing contribution of the first excited crystal electric field
doublet. At a critical point x(cr) approximate to 0.65 a second
transition appears at T-L <= T-N. In contrast to observations in
itinerant systems like CeRh2Si2 or CeRh3B2, no evidences for significant
hybridization of the 4f electrons at large Sc contents were found.
Therefore, the exceptionally large T-N of CeScGe can be attributed to an
increasing Ruderman-Kittel-Kasuya-Yosida interaction between Ce double
layers as Sc content grows.